1. Field of the Invention
THIS INVENTION concerns radiant electric heating elements particularly, though not exclusively, for heating food products where the heating element is disposed closely against the product to be heated. Such an application would be a bread toasting appliance so that the heating element is producing radiant heat in a dry environment to toast the bread.
2. Description of the Prior Art
Electrical toast making appliances, both manual and automatic have been around for many years, they were in the main constructed of a wire wound heating element embodied in a mechanism in such a manner that the material to be toasted is inserted at a suitable distance between and away from the heating elements, so as not to come into contact therewith. To overcome the disadvantage of large separation between the heating element and the toasting material, additional energy is required. Toasters are either manual or automatic. Manual toasters consist of a mechanical switch timer with a manual insert/ejector, whilst automatic toasters have an indirect browning sensor triggering a toasting material ejector to raise the bread slice to a level of safe accessibility.
Traditionally, the heating elements have consisted of an electrical resistance wire of a suitable resistance value wound round either a mica plate supported in a metal frame or on a suitable length of ceramic rod or a spiral heating element enclosed in a quartz tube. They are delicate and easily damaged.
To prevent the toasting material and the operator from coming in contact with the electrical conducting resistance wire a metal wire grid is inserted and spaced at a suitable and safe distance from the heating element, thus preventing the user from sustaining an electric shock. In addition, the grid centres the toasting material and acts both as a reflector and absorber of the energy thus reducing by a not insignificant factor the energy being received by the bread.
The above method of toasting relies essentially on the radiation of heat from the heating elements, with the minor assistance of convection. This consumes relatively high amounts of energy for the required task.